Field of the Invention and Prior Art
This invention concerns the replication of stamping dies of the type used for embossing book covers and the like.
It is known to replicate stamping dies by making a negative mold from a master stamping die, electrodepositing a thin plate (0.019" e.g.) of nickel, and a very thick plate of copper onto the negative mold to a condition wherein the mold cavity pattern is filled and a thick electroform is produced. The back of the electroform is then ground flat until all evidence of the cavity pattern is removed.
This prior art process is costly in that it requires an extended time for electrodeposition of the nickel and copper plates which, for example, can take as much as 40-70 hours. The extended electrodeposition process results in undesirable manufacturing costs due to extended periods of occupation of the electrodeposition bath and the excessive amount of die material, typically copper or nickel, which is required. The after-grinding process also adds to the cost of manufacture of die replicas by that known process.
Yet another approach is to create an electroform shell and to fill the shell cavities with Bakelite by capturing a Bakelite sheet between the electroform and the die back plate. That approach may be suitable to create stamping die replicas which are not intended for extended use or high temperature stamping, however, it is not suitable for high temperature operation (375 degrees F., e.g.) due to break-down of the Bakelite.